Prosthetic heart valve

ABSTRACT

Embodiments of a radially collapsible and expandable prosthetic heart valve are disclosed. A valve frame can have a tapered profile when mounted on a delivery shaft, with an inflow end portion having a smaller diameter than an outflow end portion. The valve can comprise generally V-shaped leaflets, reducing material within the inflow end of the frame. An outer skirt can be secured to the outside of the inflow end portion of the frame, the outer skirt having longitudinal slack when the valve is expanded and lying flat against the frame when the valve is collapsed. A diagonally woven inner skirt can elongate axially with the frame. Side tabs of adjacent leaflets can extend through and be secured to window frame portions of the frame to form commissures. The window frame portions can be depressed radially inward relative to surrounding frame portions when the valve is crimped onto a delivery shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/194,375, filed Jun. 27, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/253,689, filed Oct. 5, 2011, which claims thebenefit of U.S. Provisional Application No. 61/390,107, filed Oct. 5,2010, and U.S. Provisional Application No. 61/508,513, filed Jul. 15,2011, all of which are herein incorporated by reference.

FIELD

The present disclosure concerns embodiments of a prosthetic heart valve,and delivery systems for implanting heart valves.

BACKGROUND

The human heart can suffer from various valvular diseases. Thesevalvular diseases can result in significant malfunctioning of the heartand ultimately require replacement of the native valve with anartificial valve. There are a number of known artificial valves and anumber of known methods of implanting these artificial valves in humans.

Various surgical techniques may be used to replace or repair a diseasedor damaged valve. Due to stenosis and other heart valve diseases,thousands of patients undergo surgery each year wherein the defectivenative heart valve is replaced by a prosthetic valve. Another lessdrastic method for treating defective valves is through repair orreconstruction, which is typically used on minimally calcified valves.The problem with surgical therapy is the significant risk it imposes onthese chronically ill patients with high morbidity and mortality ratesassociated with surgical repair.

When the native valve is replaced, surgical implantation of theprosthetic valve typically requires an open-chest surgery during whichthe heart is stopped and patient placed on cardiopulmonary bypass (aso-called “heart-lung machine”). In one common surgical procedure, thediseased native valve leaflets are excised and a prosthetic valve issutured to the surrounding tissue at the valve annulus. Because of thetrauma associated with the procedure and the attendant duration ofextracorporeal blood circulation, some patients do not survive thesurgical procedure or die shortly thereafter. It is well known that therisk to the patient increases with the amount of time required onextracorporeal circulation. Due to these risks, a substantial number ofpatients with defective native valves are deemed inoperable becausetheir condition is too frail to withstand the procedure. By someestimates, more than 50% of the subjects suffering from valve stenosiswho are older than 80 years cannot be operated on for valve replacement.

Because of the drawbacks associated with conventional open-heartsurgery, percutaneous and minimally-invasive surgical approaches aregarnering intense attention. In one technique, a prosthetic valve isconfigured to be implanted in a much less invasive procedure by way ofcatheterization. For instance, U.S. Pat. Nos. 5,411,522 and 6,730,118,which are incorporated herein by reference, describe collapsibletranscatheter heart valves that can be percutaneously introduced in acompressed state on a catheter and expanded in the desired position byballoon inflation or by utilization of a self-expanding frame or stent.

An important design parameter of a transcatheter heart valve is thediameter of the folded or crimped profile. The diameter of the crimpedprofile is important because it directly influences the physician'sability to advance the transcatheter heart valve through the femoralartery or vein. More particularly, a smaller profile allows fortreatment of a wider population of patients, with enhanced safety.

SUMMARY

The present disclosure is directed toward methods and apparatusesrelating to prosthetic valves, such as heart valves, deliveryapparatuses, and assemblies of heart valves mounted on deliveryapparatuses.

An exemplary embodiment of an assembly for implanting a prosthetic heartvalve in a patient's body comprises a delivery apparatus comprising anelongated shaft and a radially expandable prosthetic heart valve mountedon the shaft in a radially collapsed configuration for delivery into thebody. The prosthetic heart valve comprises an annular frame having aninflow end portion and an outflow end portion, and a leaflet structurepositioned within the frame. The outer diameter of the inflow endportion of the frame is smaller than the outer diameter of the outflowend portion of the frame. The reduced diameter of the inflow end can bedue to a reduce amount of materials positioned within the inflow endportion of the frame. The reduced diameter at the inflow end portion canmake room for an outer skirt positioned around the inflow end portion.

In some embodiments, the heart valve can further comprise an outer skirtpositioned around an outer surface of the inflow end portion of theframe such that an outer diameter of an inflow end portion of theprosthetic valve, inclusive of the outer skirt, is still less than orequal to an outer diameter of an outflow end portion of the prostheticvalve.

In some embodiments, the leaflet structure can comprise a plurality ofleaflets that each comprises opposing side tabs on opposite sides of theleaflet. The side tabs can be secured to the outflow end portion of theframe. Each leaflet can further comprise a free outflow edge portionextending between the side tabs adjacent to the outflow end of the frameand an inflow edge portion extending between the side tabs adjacent tothe inflow end of the frame. The inflow edge portion can compriseopposing axial edge portions that extend from the side tabs toward theinflow end in a generally axial direction and an intermediate edgeportion that extends between the axial edge portions. The intermediateedge portion can comprise a curved apex portion adjacent to the inflowend of the frame and a pair of oblique portions that extend between theaxial edge portions and the apex portion. The oblique portions can havea greater radius of curvature than the apex portion, forming a generallyV-shaped leaflet.

In some embodiments, the frame comprises a plurality of angularly spacedcommissure windows each comprising an enclosed opening between first andsecond axially oriented side struts. In these embodiments, the leafletstructure comprises a plurality of leaflets each comprising two opposingside tabs, each side tab being paired with an adjacent side tab of anadjacent leaflet to form commissures of the leaflet structure. Eachcommissure extends radially outwardly through a corresponding commissurewindow of the frame to a location outside of the frame and is sutured tothe side struts of the commissure window. In some of these embodiments,the commissure windows of the frame are depressed radially inwardlyrelative to the portions of the frame extending between adjacentcommissure windows when the prosthetic valve is in the collapsedconfiguration on the shaft.

In some embodiments, the frame comprises an inflow row of openings atthe inflow end portion of the frame, an outflow row of openings at theoutflow end portion of the frame, and at least one intermediate row ofopenings between the inflow row of openings and outflow row of openings.The openings of the inflow row of openings are larger than the openingsof the at least one intermediate row of openings.

In some embodiments, portions of the leaflet structure protrude throughopenings in the frame while in the collapsed configuration on the shaft.

In some embodiments, the inflow end portion of the frame comprises aframe thickness that is less than a frame thickness of an intermediateportion of the frame between the inflow end portion and the outflow endportion.

Embodiments disclosed here can comprise an implantable prosthetic valvethat is radially collapsible to a collapsed configuration and radiallyexpandable to an expanded configuration. Such prosthetic valves cancomprise an annular frame, a leaflet structure positioned within theframe, and an annular outer skirt positioned around an outer surface ofthe frame. The outer skirt can comprise an inflow edge secured to theframe at a first location, an outflow edge secured to the frame at asecond location, and an intermediate portion between the inflow edge andthe outflow edge. When the valve is in the expanded configuration, theintermediate portion of the outer skirt comprises slack in the axialdirection between the inflow edge of the outer skirt and the outflowedge of the outer skirt, and when the valve is collapsed to thecollapsed configuration, the axial distance between the inflow edge ofthe outer skirt and the outflow edge of the outer skirt increases,reducing the slack in the outer skirt in the axial direction.

In some of these embodiments, the outer skirt is not stretched in theaxial direction when the valve is radially collapsed to the collapsedconfiguration and slack is removed from the intermediate portion of theouter skirt.

Some embodiments of an implantable prosthetic valve comprise an annularframe comprising a plurality of leaflet attachment portions, and aleaflet structure positioned within the frame and secured to the leafletattachment portions of the frame. The leaflet structure comprises aplurality of leaflets, each leaflet comprising a body portion, twoopposing primary side tabs extending from opposite sides of the bodyportion, and two opposing secondary tabs extending from the bodyadjacent to the primary side tabs. The secondary tabs are folded about aradially extending crease such that a first portion of the secondarytabs lies flat against the body portion of the respective leaflet, andthe secondary tabs are folded about an axially extending crease suchthat a second portion of the secondary tabs extends in a different planethan the first portion. The second portion of each secondary tab issutured to a respective primary tab and the secondary tabs arepositioned inside of the frame.

In some of these embodiments, the first portion of each the secondarytab pivots about the axially extending crease and lays flat against thesecond portion of the secondary tab when the valve is collapsed to aradially collapsed configuration. The first portion of each secondarytab comprises an inner edge spaced radially from an inner surface of theframe, and the body portion of the leaflet articulates about the inneredges of the two secondary tabs of the leaflet in response to bloodflowing through the valve when the valve is in operation within apatient's body.

Some embodiments disclosed herein comprise an implantable prostheticvalve that is radially collapsible to a collapsed configuration andradially expandable to an expanded configuration. The prosthetic valvecomprises an annular frame having an inflow end portion and an outflowend portion, a leaflet structure positioned within the frame, and anannular inner skirt positioned within the frame. The inner skirt issecured to the inside of the frame and the inner skirt comprises a weaveof a first set of strands with a second set of strands, both the firstand second sets of strands being non-parallel with the axial directionof the valve. When the valve is collapsed from the expandedconfiguration to the collapsed configuration, the axial length of theframe increases and the both the first and second sets of strands rotatetoward the axial direction of the valve, allowing the inner skirt toelongate in the axial direction along with the frame.

In some of these embodiments, the first set of strands are substantiallyperpendicular to the second set of strands when the valve is in theexpanded configuration. In some embodiments, the first set of strandsforms a first angle with the axial direction of the valve and the secondset of strands forms a second angle with the axial direction of thevalve, the first and second angles being substantially equal. In some ofthese embodiments, the first and second sets of strands comprise20-denier yarn.

Some embodiments of an implantable prosthetic valve comprise a radiallycollapsible and expandable annular frame comprising a plurality ofangularly spaced commissure windows each comprising an enclosed openingbetween first and second axially oriented side struts. The valve alsocomprises a leaflet structure positioned within the frame and comprisinga plurality of leaflets each comprising two opposing side tabs. Eachside tab is paired with an adjacent side tab of an adjacent leaflet toform commissures of the leaflet structure. Each pair of side tabsextends radially outwardly through a corresponding commissure window toa location outside of the frame, the portions of the tabs locatedoutside of the frame extending circumferentially away from one anotherand along an exterior surface of the side struts. The valve furthercomprises a plurality of wedges, each wedge being positioned between theside struts of a commissure window and separating the pair of side tabsextending through the commissure window, the wedge being urged radiallyinwardly against the side tabs.

The wedges can be elongated in an axial direction and correspond inaxial length with an axial length of the side struts of the commissurewindows. The wedges can further restrict rotational movement of the pairof side tabs relative to the commissure window. Each wedge can besutured to a flexible reinforcing sheet that is also sutured to each ofthe pair of side tabs, and each can be sutured to the pair of side tabs.The wedges can comprise a non-metallic material, such as suturematerial.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 show an exemplary embodiment of a prosthetic heart valve.

FIGS. 4-10 show an exemplary frame of the heart valve of FIG. 1.

FIGS. 11, 12, 13, 14, 15A, and 15B show another exemplary frame for usein a prosthetic heart valve.

FIGS. 16A and 16B show an exemplary inner skirt of the heart valve ofFIG. 1.

FIG. 17 shows another embodiment of a prosthetic heart valve in acompressed (crimped) condition with a deformed frame.

FIG. 18 shows the heart valve of FIG. 1 in a compressed state andmounted on an exemplary balloon catheter.

FIGS. 19A, 19B, and 20 show the assembly of the inner skirt of FIG. 16Awith the frame of FIG. 4.

FIGS. 21-28 show the assembly of an exemplary leaflet structure.

FIGS. 29-35 show the assembly of commissure portions of the leafletstructure with window frame portions of the frame.

FIGS. 36-40 show the assembly of the leaflet structure with the innerskirt along a lower edge of the leaflets.

FIG. 41 shows an exemplary outer skirt laid out flat.

FIGS. 42 and 43 show the exemplary prosthetic heart valve of FIG. 1.

FIGS. 44-48 show an alternative embodiment of a prosthetic heart valve.

FIGS. 49-52 show portions of an alternative embodiment of a frame.

FIG. 53 shows a portion of the frame of FIG. 4 in a radially compressedstate.

FIG. 54 shows a cross-sectional profile of the frame of FIG. 4, showingsa general tapering from the outflow end to the inflow end.

FIG. 55 shows the frame of FIG. 4 in an unrolled, flat configuration.

FIG. 56 shows the heart valve of FIG. 1 in a compressed state andmounted on an exemplary balloon catheter.

FIGS. 57 and 58 shows an embodiment of a leaflet have a generallyV-shaped configuration.

FIG. 59 shows a cross-sectional view of an alternative embodiment of aprosthetic valve having a variable thickness frame.

FIG. 60 is a side view of an embodiment of a frame of a valve havingcommissure windows, prior to mounting a leaflet structure to the frame.

FIG. 60A is an enlarged side view of one commissure window of FIG. 60.

FIG. 61 is a perspective view of an embodiment of a prosthetic valvecomprising the frame of FIG. 60 and a leaflet structure mounted to thevalve.

FIG. 62 is an enlarged side view of one commissure of the valve of FIG.61.

FIGS. 63-71 are cross-sectional views of a commissure of the valve ofFIG. 61 showing various techniques for suturing a pair of leaflet sidetabs to a commissure window using a reinforcing sheet.

FIGS. 72-74 show balloon expansion of an alternative embodiment of aframe for a prosthetic valve having inflow and outflow end portions ofreduced thickness.

DETAILED DESCRIPTION

FIGS. 1-3 show various views of a prosthetic heart valve 10, accordingto one embodiment. The illustrated valve is adapted to be implanted inthe native aortic annulus, although in other embodiments it can beadapted to be implanted in the other native annuluses of the heart. Thevalve 10 can have four main components: a stent, or frame, 12, avalvular structure 14, an inner skirt 16, and an outer skirt 18.

The valvular structure 14 can comprise three leaflets 40, collectivelyforming a leaflet structure, which can be arranged to collapse in atricuspid arrangement, as best shown in FIG. 2. The lower edge ofleaflet structure 14 desirably has an undulating, curved scalloped shape(suture line 154 shown in FIG. 1 tracks the scalloped shape of theleaflet structure). By forming the leaflets with this scallopedgeometry, stresses on the leaflets are reduced, which in turn improvesdurability of the valve. Moreover, by virtue of the scalloped shape,folds and ripples at the belly of each leaflet (the central region ofeach leaflet), which can cause early calcification in those areas, canbe eliminated or at least minimized. The scalloped geometry also reducesthe amount of tissue material used to form leaflet structure, therebyallowing a smaller, more even crimped profile at the inflow end of thevalve. The leaflets 40 can be formed of pericardial tissue (e.g., bovinepericardial tissue), biocompatible synthetic materials, or various othersuitable natural or synthetic materials as known in the art anddescribed in U.S. Pat. No. 6,730,118, which is incorporated by referenceherein.

The bare frame 12 is shown in FIG. 4. The frame 12 can be formed with aplurality of circumferentially spaced slots, or commissure windows, 20(three in the illustrated embodiment) that are adapted to mount thecommissures of the valvular structure 14 to the frame, as described ingreater detail below. The frame 12 can be made of any of varioussuitable plastically-expandable materials (e.g., stainless steel, etc.)or self-expanding materials (e.g., Nitinol) as known in the art. Whenconstructed of a plastically-expandable material, the frame 12 (and thusthe valve 10) can be crimped to a radially compressed state on adelivery catheter and then expanded inside a patient by an inflatableballoon or equivalent expansion mechanism. When constructed of aself-expandable material, the frame 12 (and thus the valve 10) can becrimped to a radially compressed state and restrained in the compressedstate by insertion into a sheath or equivalent mechanism of a deliverycatheter. Once inside the body, the valve can be advanced from thedelivery sheath, which allows the valve to expand to its functionalsize.

Suitable plastically-expandable materials that can be used to form theframe 12 include, without limitation, stainless steel, a nickel basedalloy (e.g., a cobalt-chromium or a nickel-cobalt-chromium alloy),polymers, or combinations thereof. In particular embodiments, frame 12is made of a nickel-cobalt-chromium-molybdenum alloy, such as MP35N™(tradename of SPS Technologies), which is equivalent to UNS R30035(covered by ASTM F562-02). MP35N™/UNS R30035 comprises 35% nickel, 35%cobalt, 20% chromium, and 10% molybdenum, by weight. It has been foundthat the use of MP35N to form frame 12 provides superior structuralresults over stainless steel. In particular, when MP35N is used as theframe material, less material is needed to achieve the same or betterperformance in radial and crush force resistance, fatigue resistances,and corrosion resistance. Moreover, since less material is required, thecrimped profile of the frame can be reduced, thereby providing a lowerprofile valve assembly for percutaneous delivery to the treatmentlocation in the body.

Referring to FIGS. 4 and 5, the frame 12 in the illustrated embodimentcomprises a first, lower row I of angled struts 22 arranged end-to-endand extending circumferentially at the inflow end of the frame; a secondrow II of circumferentially extending, angled struts 24; a third row IIIof circumferentially extending, angled struts 26; a fourth row IV ofcircumferentially extending, angled struts 28; and a fifth row V ofcircumferentially extending, angled struts 32 at the outflow end of theframe. A plurality of substantially straight axially extending struts 34can be used to interconnect the struts 22 of the first row I with thestruts 24 of the second row II. The fifth row V of angled struts 32 areconnected to the fourth row IV of angled struts 28 by a plurality ofaxially extending window frame portions 30 (which define the commissurewindows 20) and a plurality of axially extending struts 31. Each axialstrut 31 and each frame portion 30 extends from a location defined bythe convergence of the lower ends of two angled struts 32 to anotherlocation defined by the convergence of the upper ends of two angledstruts 28. FIGS. 6, 7, 8, 9 and 10 are enlarged views of the portions ofthe frame 12 identified by letters A, B, C, D and E, respectively, inFIG. 4.

Each commissure window frame portion 30 mounts a respective commissureof the leaflet structure 14. As can be seen each frame portion 30 issecured at its upper and lower ends to the adjacent rows of struts toprovide a robust configuration that enhances fatigue resistance undercyclic loading of the valve compared to known cantilevered struts forsupporting the commissures of the leaflet structure. This configurationenables a reduction in the frame wall thickness to achieve a smallercrimped diameter of the valve. In particular embodiments, the thicknessT of the frame 12 (FIG. 4) measured between the inner diameter and outerdiameter is about 0.48 mm or less.

The struts and frame portions of the frame collectively define aplurality of open cells of the frame. At the inflow end of the frame 12,struts 22, struts 24, and struts 34 define a lower row of cells definingopenings 36. The second, third, and fourth rows of struts 24, 26, and 28define two intermediate rows of cells defining openings 38. The fourthand fifth rows of struts 28 and 32, along with frame portions 30 andstruts 31, define an upper row of cells defining openings 40. Theopenings 40 are relatively large and are sized to allow portions of theleaflet structure 14 to protrude, or bulge, into and/or through theopenings 40 when the frame 12 is crimped in order to minimize thecrimping profile.

As best shown in FIG. 7, the lower end of the strut 31 is connected totwo struts 28 at a node or junction 44, and the upper end of the strut31 is connected to two struts 32 at a node or junction 46. The strut 31can have a thickness S1 that is less than the thicknesses S2 of thejunctions 44, 46. FIG. 53 shows a portion of the frame 12 in a crimpedstate. The junctions 44, 46, along with junctions 64, prevent fullclosure of openings 40. FIG. 18 shows the valve 10 crimped on a ballooncatheter. As can be seen, the geometry of the struts 31, and junctions44, 46 and 64 assists in creating enough space in openings 40 in thecrimped state to allow portions of the leaflets to protrude (i.e.,bulge) outwardly through openings. This allows the valve to be crimpedto a relatively smaller diameter than if all of the leaflet material isconstrained within the crimped frame.

The frame 12 is configured to prevent or at least minimize possibleover-expansion of the valve at a predetermined balloon pressure,especially at the outflow end portion of the frame, which supports theleaflet structure 14. In one aspect, the frame is configured to haverelatively larger angles 42 a, 42 b, 42 c, 42 d, 42 e between struts.The larger the angle, the greater the force required to open (expand)the frame. This phenomenon is schematically illustrated in FIGS. 15A and15B. FIG. 15A shows a strut 32 when the frame 12 is in its compressedstate (e.g., mounted on a balloon). The vertical distance d₁ between theends of the struts is greatest when the frame is compressed, providing arelatively large moment between forces F₁ and F₂ acting on the ends ofthe strut in opposite directions upon application of an opening forcefrom inflation of the balloon (or expansion of another expansiondevice). When the frame expands radially, the vertical distance betweenthe ends of the strut decreases to a distance d₂, as depicted in FIG.15B. As the vertical distance decreases, so does the moment betweenforces F₁ and F₂. Hence, it can be seen that a relatively greaterexpansion force is required as the vertical distance and the momentbetween the ends of the strut decreases. Moreover, strain hardening(stiffening) at the ends of the strut increases as the frame expands,which increases the expansion force required to induce further plasticdeformation at the ends of the strut. As such, the angles between thestruts of the frame can be selected to limit radial expansion of theframe at a given opening pressure (e.g., inflation pressure of theballoon). In particular embodiments, these angles are at least 110degrees or greater when the frame is expanded to its functional size,and even more particularly these angles are at least 120 degrees orgreater when the frame is expanded to its functional size.

In addition, the inflow and outflow ends of a frame generally tend toover-expand more so than the middle portion of the frame due to the “dogboning” effect of the balloon used to expand the valve. To protectagainst over-expansion of the leaflet structure 14, the leafletstructure desirably is secured to the frame 12 below the upper row ofstruts 32, as best shown in FIG. 1. FIG. 55 shows a flattened view ofthe frame 12 similar to FIG. 5, but showing a line 176 superimposed overthe frame to indicate the position of the upper edges of the leaflets40. Thus, in the event that the outflow end of the frame isover-expanded, the leaflet structure is positioned at a level belowwhere over-expansion is likely to occur, thereby protecting the leafletstructure from over-expansion.

In a known valve construction, the leaflets can protrude outwardlybeyond the outflow end of the frame when the valve is crimped if theleaflets are mounted too close to the distal end of the frame. If thedelivery catheter on which the crimped valve is mounted includes apushing mechanism or stop member that pushes against or abuts theoutflow end of the valve (for example, to maintain the position of thecrimped valve on the delivery catheter), the pushing member or stopmember can damage the exposed leaflets that extend beyond the outflowend of the frame. Another benefit of mounting the leaflets at a locationspaced from the outflow end 178 of the frame is that when the valve iscrimped on a delivery catheter, as shown in FIG. 56, the leaflets 40 donot protrude beyond the outflow end 178 of the frame in the axialdirection. As such, if the delivery catheter includes a pushingmechanism or stop member that pushes against or abuts the outflow end ofthe valve, the pushing mechanism or stop member can contact the end 178of the frame, and not leaflets 40, so as to avoid damage to theleaflets.

Also, as can be seen in FIG. 5, the openings 36 of the lowermost row ofopenings in the frame are relatively larger than the openings 38 of thetwo intermediate rows of openings. As shown in FIG. 54, this allows theframe, when crimped, to assume an overall tapered shape that tapers froma maximum diameter D₁ at the outflow end of the valve to a minimumdiameter D₂ at the inflow end of the valve. When crimped, the frame 12has a reduced diameter region extending along a portion of the frameadjacent the inflow end of the frame, indicated by reference number 174,that generally corresponds to the region of the frame covered by theouter skirt 18. The diameter of region 174 is reduced compared to thediameter of the upper portion of the frame (which is not covered by theouter skirt) such that the outer skirt 18 does not increase the overallcrimp profile of the valve. When the valve is deployed, the frame canexpand to the cylindrical shape shown in FIG. 4. In one example, theframe of a 26-mm valve, when crimped, had a diameter D₁ of 14 French atthe outflow end of the valve and a diameter D₂ of 12 French at theinflow end of the valve.

FIGS. 11 and 12 show an alternative frame 50 that can be incorporated inthe valve 10. The frame 50 comprises multiple rows of circumferentiallyextending, angled struts 52 that are connected to each other at nodes,or connecting portions, 54 and 56. The uppermost row of struts 52 areconnected to an adjacent row of struts by a plurality of axiallyextending struts 58 and commissure window frame portions 60. Eachcommissure frame portion 60 defines a slot, or commissure window, 62 formounting a respective commissure of the valvular structure, as describedin greater detail below. In particular embodiments, the thickness T ofthe frame 50 is about 0.45 mm or less. FIGS. 13 and 14 are enlargedviews of the portions of the frame 50 identified by letters A and B,respectively, in FIG. 12.

The main functions of the inner skirt 16 are to assist in securing thevalvular structure 14 to the frame 12 and to assist in forming a goodseal between the valve and the native annulus by blocking the flow ofblood through the open cells of the frame 12 below the lower edge of theleaflets. The inner skirt 16 desirably comprises a tough, tear resistantmaterial such as polyethylene terephthalate (PET), although variousother synthetic or natural materials can be used. The thickness of theskirt desirably is less than 6 mil, and desirably less than 4 mil, andeven more desirably about 2 mil. In particular embodiments, the skirt 16can have a variable thickness, for example, the skirt can be thicker atits edges than at its center. In one implementation, the skirt 16 cancomprise a PET skirt having a thickness of about 0.07 mm at its edgesand about 0.06 mm at its center. The thinner skirt can provide forbetter crimping performances while still providing good perivalvularsealing.

The skirt 16 can be secured to the inside of frame 12 via sutures 70, asshown in FIG. 39. Valvular structure 14 can be attached to the skirt viaone or more thin PET reinforcing strips 72 (which collectively can forma sleeve), discussed below, which enables a secure suturing and protectsthe pericardial tissue of the leaflet structure from tears. Valvularstructure 14 can be sandwiched between skirt 16 and the thin PET strips72 as shown in FIG. 38. Sutures 154, which secure the PET strip and theleaflet structure 14 to skirt 16, can be any suitable suture, such as anEthibond suture. Sutures 154 desirably track the curvature of the bottomedge of leaflet structure 14, as described in more detail below.

Known fabric skirts comprise a weave of warp and weft fibers that extendperpendicular to each other and with one set of fibers extendingperpendicularly to the upper and lower edges of the skirt. When themetal frame, to which the fabric skirt is secured, is radiallycompressed, the overall axial length of the frame increases.Unfortunately, a fabric skirt, which inherently has limited elasticity,cannot elongate along with the frame and therefore tends to deform thestruts of the frame and prevents uniform crimping.

FIG. 17 shows an example of a crimped valve where the struts have beendeformed in several places, as indicated by reference number 100, by askirt having fibers that extend perpendicular to the upper and loweredges of the skirt. Moreover, the fabric tends to bunch or create bulgesof excess material in certain locations, which limits the minimumcrimping profile and prevents uniform crimping.

Referring to FIG. 16B, in contrast to known fabric skirts, the skirt 16desirably is woven from a first set of fibers, or yarns or strands, 78and a second set of fibers, or yarns or strands, 80, both of which arenon-perpendicular to the upper edge 82 and the lower edge 84 of theskirt. In particular embodiments, the first set of fibers 78 and thesecond set of fibers 80 extend at angles of about 45 degrees relative tothe upper and lower edges 82, 84. The skirt 16 can be formed by weavingthe fibers at 45 degree angles relative to the upper and lower edges ofthe fabric. Alternatively, the skirt can be diagonally cut from avertically woven fabric (where the fibers extend perpendicular to theedges of the material) such that the fibers extend at 45 degree anglesrelative to the cut upper and lower edges of the skirt. As further shownin FIG. 16B, the opposing short edges 86, 88 of the skirt desirably arenon-perpendicular to the upper and lower edges 82, 84. For example, theshort edges 86, 88 desirably extend at angles of about 45 degreesrelative to the upper and lower edges and therefore are aligned with thefirst set of fibers 78. Therefore the overall shape of the skirt is thatof a rhomboid.

FIGS. 19A and 19B shows the skirt 16 after opposing edge portions 90, 92have been sewn together to form the annular shape of the skirt. Asshown, the edge portion 90 can be placed in an overlapping relationshiprelative to the opposite edge portion 92, and the two edge portions canbe sewn together with a diagonally extending suture line 94 that isparallel to edges 86, 88. The upper edge portion of the skirt 16 can beformed with a plurality of projections 96 that define an undulated shapethat generally follows the shape of the fourth row of struts 28immediately adjacent the lower ends of axial struts 31. In this manner,as best shown in FIG. 20, the upper edge of skirt 16 can be tightlysecured to struts 28 with sutures 70. Skirt 16 can also be formed withslits 98 to facilitate attachment of the skirt to the frame. Slits 98are dimensioned so as to allow an upper edge portion of skirt to bepartially wrapped around struts 28 and reduce stresses in the skirtduring the attachment procedure. For example, in the illustratedembodiment, skirt 16 is placed on the inside of frame 12 and an upperedge portion of the skirt is wrapped around the upper surfaces of struts28 and secured in place with sutures 70. Wrapping the upper edge portionof the skirt around struts 28 in this manner provides for a stronger andmore durable attachment of the skirt to the frame. The skirt 16 can alsobe secured to the first, second, and third rows of struts 22, 24, and26, respectively, with sutures 70.

Referring again to FIG. 16B, due to the orientation of the fibersrelative to the upper and lower edges, the skirt can undergo greaterelongation in the axial direction (i.e., in a direction from the upperedge 82 to the lower edge 84).

Thus, when the metal frame 12 is crimped (as shown in FIG. 18), theskirt 16 can elongate in the axial direction along with the frame andtherefore provides a more uniform and predictable crimping profile. Eachcell of the metal frame in the illustrated embodiment includes at leastfour angled struts that rotate towards the axial direction (i.e., theangled struts become more aligned with the length of the frame). Theangled struts of each cell function as a mechanism for rotating thefibers of the skirt in the same direction of the struts, allowing theskirt to elongate along the length of the struts. This allows forgreater elongation of the skirt and avoids undesirable deformation ofthe struts when the valve is crimped.

In addition, the spacing between the woven fibers or yarns can beincreased to facilitate elongation of the skirt in the axial direction.For example, for a PET skirt 16 formed from 20-denier yarn, the yarndensity can be about 15% to about 30% less than a conventional PETskirt. In some examples, the yarn spacing of the skirt 16 can be fromabout 155 yarns per inch to about 180 yarns per inch, such about 160yarns per inch, whereas in a conventional PET skirt the yarn spacing canbe from about 217 yarns per inch to about 247 yarns per inch. Theoblique edges 86, 88 promote uniform and even distribution of the fabricmaterial along inner circumference of the frame during crimping so as tominimize bunching of the fabric to facilitate uniform crimping to thesmallest possible diameter. Additionally, cutting diagonal sutures in avertical manner may leave loose fringes along the cut edges. The obliqueedges 86, 88 help minimize this from occurring. As noted above, FIG. 17shows a crimped valve with a conventional skirt that has fibers that runperpendicular to the upper and lower edges of the skirt. Comparing FIGS.17 and 18, it is apparent that the construction of skirt 16 avoidsundesirable deformation of the frame struts and provides more uniformcrimping of the frame.

In alternative embodiments, the skirt can be formed from woven elasticfibers that can stretch in the axial direction during crimping of thevalve. The warp and weft fibers can run perpendicular and parallel tothe upper and lower edges of the skirt, or alternatively, they canextend at angles between 0 and 90 degrees relative to the upper andlower edges of the skirt, as described above.

The inner skirt 16 can be sutured to the frame 12 at locations away fromthe suture line 154 so that the skirt can be more pliable in that area(see FIG. 28). This can avoid stress concentrations at the suture line154, which attaches the lower edges of the leaflets to the skirt 16.

As noted above, the leaflet structure 14 in the illustrated embodimentincludes three flexible leaflets 40 (although a greater or fewer numberof leaflets can be used). As best shown in FIG. 21, each leaflet 40 inthe illustrated configuration has an upper (outflow) free edge 110extending between opposing upper tabs 112 on opposite sides of theleaflet. Below each upper tab 112 there is a notch 114 separating theupper tab from a corresponding lower tab 116. The lower (inflow) edgeportion 108 of the leaflet extending between respective ends of thelower tabs 116 includes vertical, or axial, edge portions 118 onopposites of the leaflets extending downwardly from corresponding lowertabs 116 and a substantially V-shaped, intermediate edge portion 120having a smooth, curved apex portion 119 at the lower end of the leafletand a pair of oblique portions 121 that extend between the axial edgeportions and the apex portion. The oblique portions can have a greaterradius of curvature than the apex portion. Each leaflet 40 can have areinforcing strip 72 secured (e.g., sewn) to the inner surface of thelower edge portion 108, as shown in FIG. 22.

The leaflets 40 can be secured to one another at their adjacent sides toform commissures 122 of the leaflet structure. A plurality of flexibleconnectors 124 (one of which is shown in FIG. 23) can be used tointerconnect pairs of adjacent sides of the leaflets and to mount theleaflets to the commissure window frame portions 30. The flexibleconnectors 124 can be made from a piece of woven PET fabric, althoughother synthetic and/or natural materials can be used. Each flexibleconnector 124 can include a wedge 126 extending from the lower edge tothe upper edge at the center of the connector. The wedge 126 cancomprise a non-metallic material, such as a rope or a piece of Ethibond2-0 suture material, secured to the connector with a temporary suture128. The wedge 126 helps prevent rotational movement of the leaflet tabsonce they are secured to the commissure window frame portions 30. Theconnector 124 can have a series of inner notches 130 and outer notches132 formed along its upper and lower edges.

FIG. 24 shows the adjacent sides of two leaflets 40 interconnected by aflexible connector 124. The opposite end portions of the flexibleconnector 124 can be placed in an overlapping relationship with thelower tabs 116 with the inner notches 130 aligned with the verticaledges of the tabs 116. Each tab 116 can be secured to a correspondingend portion of the flexible connector 124 by suturing along a lineextending from an outer notch 132 on the lower edge to an outer notch132 on the upper edge of the connector. Three leaflets 40 can be securedto each other side-to-side using three flexible connectors 124, as shownin FIG. 25.

Referring now to FIGS. 26 and 27, the adjacent sub-commissure portions118 of two leaflets can be sutured directly to each other. In theexample shown, PTFE-6-0 suture material is used to form in-and-outstitches 133 and comb stitches 134 that extend through thesub-commissure portions 118 and the reinforcing strips 72 on bothleaflets. The two remaining pairs of adjacent sub-commissure portions118 can be sutured together in the same manner to form the assembledleaflet structure 14, which can then be secured to the frame 12 in thefollowing manner.

As noted above, the inner skirt 16 can be used to assist in suturing theleaflet structure 14 to the frame. As shown in FIG. 28, the skirt 16 canhave an undulating temporary marking suture 136 to guide the attachmentof the lower edges of each leaflet 40. The skirt 16 itself can besutured to the struts of the frame 12 using sutures 70, as noted above,before securing the leaflet structure 14 to the skirt 16. The strutsthat intersect the marking suture 136 desirably are not attached to theskirt 16. This allows the skirt 16 to be more pliable in the areas notsecured to the frame and minimizes stress concentrations along thesuture line that secures the lower edges of the leaflets to the skirt.The portion of the skirt 16 demarcated by rectangle 140 initially isleft unsecured to the frame 12, and is later secured to the frame afterthe leaflet structure 14 is secured to the skirt, as further describedbelow. As noted above, when the skirt is secured to the frame, thefibers 78, 80 of the skirt (see FIG. 16B) generally align with theangled struts of the frame to promote uniform crimping and expansion ofthe frame.

FIG. 29 is a cross-sectional view of a portion of the frame and leafletstructure showing the adjacent tab portions of two leaflets secured to acorresponding window frame portion 30. FIGS. 30-36 show one specificapproach for securing the commissure portions 122 of the leafletstructure 14 to the commissure window frame portions 30 of the frame.First, as shown in FIG. 30, the flexible connector 124 securing twoadjacent sides of two leaflets is folded widthwise and the upper tabportions 112 are folded downwardly against the flexible connector. Asbest shown in FIGS. 30 and 31, each upper tab portion 112 is creasedlengthwise (vertically) to assume an L-shape having an inner portion 142folded against the inner surface of the leaflet and an outer portion 144folded against the connector 124. The outer portion 144 can then besutured to the connector 124 along a suture line 146. Next, as shown inFIG. 31, the commissure tab assembly (comprised of a pair of lower tabportions 116 connected by connector 124) is inserted through thecommissure window 20 of a corresponding window frame portion 30. FIG. 32is a side view of the frame 12 showing the commissure tab assemblyextending outwardly through the window frame portion 30.

As best shown in FIGS. 29 and 33, the commissure tab assembly is pressedradially inwardly at the wedge 126 such that one of the lower tabportions 116 and a portion of the connector 124 is folded against theframe 12 on one side of the window frame portion 30 and the other lowertab portion 116 and a portion of the connector 124 is folded against theframe 12 on other side of the window frame portion 30. A pair of suturelines 148 are formed to retain the lower tab portions 116 against theframe 12 in the manner shown in FIG. 29. Each suture line 148 extendsthrough connector 124, a lower tab portion 116, the wedge 126, andanother portion of connector 124. Then, as shown in FIGS. 29 and 34,each lower tab portion 116 is secured to a corresponding upper tabportion 112 with a primary suture line 150 that extends through onelayer of connector 124, the lower tab portion 116, another layer ofconnector 124, another layer of connector 124, and the upper tab portion112. Finally, as shown in FIGS. 29 and 35, the suture material used toform the primary suture line 150 can be used to further form whipstitches 152 at the edges of the tab portions 112, 116 that extendthrough two layers of connector 124 sandwiched between tab portions 112,116.

As shown in FIGS. 29 and 30, the folded down upper tab portions 112 forma double layer of leaflet material at the commissures. The innerportions 142 of the upper tab portions 112 are positioned flat abuttinglayers of the two leaflets 40 forming the commissures, such that eachcommissure comprises four layers of leaflet material just inside of thewindow frames 30. This four layered portion of the commissures can bemore resistant to bending, or articulating, than the portion of theleaflets 40 just radially inward from the relatively more rigid fourlayered portion. This causes the leaflets 40 to articulate primarily atinner edges 143 of the folded-down inner portions 142 in response toblood flowing through the valve during operation within the body, asopposed to articulating about the axial struts of the window frames 30.Because the leaflets articulate at a location spaced radially inwardlyfrom the window frames 30, the leaflets can avoid contact with anddamage from the frame. However, under high forces, the four layeredportion of the commissures can splay apart about a longitudinal axis 145(FIG. 29) adjacent to the window frame 30, with each inner portion 142folding out against the respective outer portion 144. For example, thiscan occur when the valve 10 is compressed and mounted onto a deliveryshaft, allowing for a smaller crimped diameter. The four layered portionof the commissures can also splay apart about axis 145 when the ballooncatheter is inflated during expansion of the valve, which can relievesome of the pressure on the commissures caused by the balloon and so thecommissures are not damaged during expansion.

After all three commissure tab assemblies are secured to respectivewindow frame portions 30, the lower edges of the leaflets 40 between thecommissure tab assemblies can be sutured to the inner skirt 16. Forexample, as shown in FIGS. 36-38, each leaflet 40 can be sutured to theskirt 16 along suture line 154 using, for example, Ethibond thread. Thesutures can be in-and-out sutures extending through each leaflet 40, theskirt 16 and each reinforcing strip 72. Each leaflet 40 and respectivereinforcing strip 72 can be sewn separately to the skirt 16. In thismanner, the lower edges of the leaflets are secured to the frame 12 viathe skirt 16. As shown in FIG. 38, the leaflets can be further securedto the skirt with blanket sutures 156 that extend through eachreinforcing strip 72, leaflet 40 and the skirt 16 while looping aroundthe edges of the reinforcing strips 72 and leaflets 40. The sutures 156can be formed from PTFE suture material. FIGS. 39 and 40 show the frame12, leaflet structure 14 and the skirt 16 after securing the leafletstructure and the skirt to the frame and the leaflet structure to theskirt.

FIG. 41 shows a flattened view of the outer skirt 18 prior to itsattachment to the frame 12. The outer skirt 18 can be laser cut orotherwise formed from a strong, durable piece of material, such as wovenPET, although other synthetic or natural materials can be used. Theouter skirt 18 can have a substantially straight lower edge 160 and anupper edge 162 defining a plurality of alternating projections 164 andnotches 166. As best shown in FIG. 42, the lower edge 160 of the skirt18 can be sutured to the lower edge of the inner skirt 16 at the inflowend of the valve. As shown in FIG. 43, each projection 164 can besutured to the second rung II of struts 24 of the frame 12. The corners162 of the projections 164 can be folded over respective struts of rungII and secured with sutures 168.

As can be seen in FIGS. 1, 3 and 43, the outer skirt 18 is secured tothe frame 12 such that when the frame is in its expanded state, there isexcess material or slack between the outer skirt's lower and upper edges160, 162 that does not lie flat against the outer surface of the frame12. In other words, the outer skirt is configured with excess materialwhich causes the outer skirt to bulge outwardly as the frameforeshortens (i.e., shortens in length) during radial expansion.Accordingly, when the valve 10 is deployed within the body, the excessmaterial of the outer skirt 18 can fill in gaps between the frame 12 andthe surrounding native annulus to assist in forming a good fluid-tightseal between the valve and the native annulus. The outer skirt 18therefore cooperates with the inner skirt 16 to avoid perivalvularleakage after implantation of the valve 10. In another advantageousfeature, the slack between the lower and upper edges of the outer skirt18 allows the frame 12 to elongate axially during crimping without anyresistance from the outer skirt and the outer skirt does notsubstantially affect the outer diameter of the prosthetic valve in thecrimped condition.

FIG. 56 shows the valve 10 of FIGS. 1-3 and 42-43 mounted on anelongated shaft 180 of a delivery apparatus, forming a delivery assemblyfor implanting the valve 10 in a patient's body. The valve 10 is mountedin a radially collapsed configuration for delivery into the body. Theshaft 180 comprises an inflatable balloon 182 for expanding the balloonwithin the body, the crimped valve 10 being positioned over the deflatedballoon. The frame 12 of the valve 10, when in the radially compressed,mounted configuration, comprises an inflow end portion 174 (see FIG. 54)that has an outer diameter D₂ that is smaller than the outer diameter D₁of the outflow end portion of the frame. The tapering of the frame canbe at least partially due to the V-shaped leaflets 40, as the V-shapedleaflets have less leaflet material within the inflow end portion of theframe 12 compared to a more rounded, U-shaped leaflet. Due to thetapered shape of the frame 12 in the mounted state, even with theadditional thickness of the outer skirt 18 positioned around the inflowend portion 174 of the frame 12 the overall outer diameter of the inflowend portion of the valve 10 can be about equal to, or less than, theoverall outer diameter of the outflow end portion of the valve.

Furthermore, as shown in FIG. 56, the valve 10 comprises commissureportions of the leaflets extending radially outwardly throughcorresponding window frame portion 30 to locations outside of the frameand sutured to the side struts of the commissure window frame. Tominimize the crimp profile of the valve, the window frame portions 30can be depressed radially inwardly relative to the surrounding portionsof the frame, such as the frame portions extending between adjacentcommissure windows, when the valve is radially compressed to thecollapsed configuration on the shaft. For example, the commissurewindows 30 of the frame can be depressed inwardly a radial distance ofbetween 0.2 mm and 1.0 mm relative to the portions of the frameextending between adjacent commissure windows when the valve is radiallycollapsed. In this way, the outer diameter of the outflow end portionthe valve comprising the commissure portions can be generallyconsistent, as opposed to the commissure portions jutting outward fromthe surrounding portions of the valve, which could hinder delivery ofthe valve into the body. Even with the radially depressed commissurewindow frames 30, the outer diameter of the inflow end portion of theframe can still be smaller than, or about equal to, the outer diameterof the outflow end portion of the frame when the valve is radiallycollapsed on the shaft, allowing for a minimal maximum overall diameterof the valve. By minimizing the diameter of the valve when mounted onthe delivery shaft, the assembly can contained within a smaller diametercatheter and thus can be passed through smaller vessels in the body andcan be less invasive in general.

FIG. 44 illustrates a prosthetic heart valve 200, according to anotherembodiment. The heart valve 200 includes a frame, or stent, 202 and aleaflet structure 204 mounted on the stent. The leaflet structure 204can include a plurality of leaflets 218 (e.g., three, as depicted),which can be sutured to each other and to the frame 202 using suitabletechniques and/or mechanisms. The frame 202 can be adapted to includecommissure frame portions 30 (as shown in FIG. 4) to assist in suturingthe leaflets to the frame.

The frame 202 shares some design features of the frame 12 describedabove. In particular, like frame 12, the frame 202 has relatively largeframe openings 206 along the area of the frame that supports the leafletstructure, as shown in FIG. 45. The openings 206 are defined by a row ofangled struts 208 at the outflow end of the frame, a plurality ofaxially extending, circumferentially spaced struts 210, and anintermediate row of angled struts 212. As shown, the axial struts 210desirably are thinner than the junctions 214 connecting the oppositeends of the axial struts 210 to the convergence of two struts 212 and tothe convergence of two struts 208. By virtue of this configuration, thewidth of openings 206 remain large enough when the valve is radiallycompressed to a delivery configuration to allow portions of the leafletstructure 204 to protrude outwardly through the openings, as indicatedat 216 in FIGS. 46 and 47. This allows the valve to be crimped to arelatively smaller diameter than if all of the leaflet material isconstrained within the crimped frame.

For purposes of comparison, FIG. 48 is a cross section of a knownprosthetic valve 250 showing the valve in its crimped state. When thevalve is radially compressed, the spacing between adjacent struts isrelatively small and does not allow portions of the leaflet structure toprotrude outwardly through the frame. Consequently, the presence of allof the leaflet material being constrained within the inside of the framelimits the crimping diameter of the valve.

FIGS. 49 and 50 show a flattened section of an alternative frameconstruction that can allow portions of the leaflets to protrudeoutwardly through the frame in the crimped state. This frameconstruction can be implemented in the valve 10 described above. FIG. 49shows the frame section in the radially compressed state while FIG. 50shows the frame section in the radially expanded state. The frame (onlya portion of which is shown) includes a first, circumferentiallyextending row of angled struts 442 and at least a second,circumferentially extending row of angled struts 444. Some openings inthe frame are diamond shaped openings 446 formed by adjacent struts 442connected to each other at their upper ends and adjacent struts 444connected to each other at their lower ends. The frame also includeslarger openings 448 that are formed by adjacent struts 442 connected attheir upper ends to respective ends of a horizontal strut 450 and byadjacent struts 444 connected at their lower ends to respective ends ofa horizontal strut 452. When the frame is radially compressed, thehorizontal struts 450, 452 maintains the width W of openings 448 largeenough to permit portions of the valve's leaflets to protrude outwardlythrough the frame. Thus, the width of openings 448 is greater than thewidth of openings 446 when the frame is crimped. The frame can be formedwith openings 446, 448 alternating around the circumference of theframe. Alternatively, openings 448 can be located at selected positionsalong the frame's length and circumference to correspond to areas wherethe leaflet material tend to bunch up within the frame, such as betweenthe commissures.

FIGS. 51 and 52 show a flattened section of another frame constructionthat can allow portions of the leaflets to protrude outwardly throughthe frame in the crimped state. This frame construction can beimplemented in the valve 10 described above. FIG. 51 shows the framesection in the radially compressed state while FIG. 52 shows the framesection in the radially expanded state. The frame (only a portion ofwhich is shown) includes a first, circumferentially extending row ofangled struts 402 and at least a second, circumferentially extending rowof angled struts 404. Some openings in the frame are diamond shapedopenings 406 formed by adjacent struts 402 connected to each other attheir upper ends and adjacent struts 404 connected to each other attheir lower ends. The frame also includes openings 408 that are formedby adjacent struts 402 connected at their upper ends to an enlarged nodeor junction 410 and by adjacent struts 404 connected at their lower endsto an enlarged node or junction 412. The junctions 410, 412 add rigidityto the frame at those locations such that when the frame is radiallycompressed, the width W of openings 408 remains large enough to permitportions of the valve's leaflets to protrude outwardly through theframe. Thus, the width of openings 408 is greater than the width ofopenings 406 when the frame is crimped. The frame can be formed withopenings 406, 408 alternating around the circumference of the frame.Alternatively, openings 408 can be located at selected positions alongthe frame's length and circumference to correspond to areas where theleaflet material tend to bunch up within the frame, such as between thecommissures.

FIG. 57 shows a leaflet 500 for a prosthetic valve (e.g., valve 10 or200), according to another embodiment. The leaflet 500 has an overallV-shape, similar to leaflets 40 described above. The leaflet 500 has twotab portions 502 on opposite sides of the leaflets which are secured toadjacent tab portions of other leaflets to form the commissures of theleaflet structure. The sub-commissure portion of the leaflet 500 (theportion below the tabs 502) include two substantially straight edges 504that extend from respective locations just below the tabs 502 to acurved lower edge 506. FIG. 58 shows the general shape of the leaflet500 when the valve is crimped. The frame (not shown in FIGS. 57-58)slightly elongates when crimped, causing the leaflet 500 to becomeslightly elongated.

The tapered profile of the sub-commissure portion of the leaflet reducesthe amount of leaflet material in the lower half of the crimped valve tominimize the crimp diameter of that portion of the valve. Thus, ifadditional components are mounted to that portion of the valve, such asan outer skirt 18, the reduced profile of that portion of the valve canhelp offset or minimize the increase in diameter caused by theadditional component. Additionally, the commissure tabs 502 arerelatively short and require less sutures for forming the commissures ofthe leaflet structure than known leaflet designs (such as T-shaped andscalloped leaflets), which better distributes and reduces the bulkinessof the leaflet material when the valve is crimped.

FIG. 59 shows a cross-sectional view of a valve 500, according toanother embodiment. The valve 500 comprises a frame 502, leaflets 504,and an outer skirt 18 mounted (e.g., by sutures) to the outer surface ofthe frame 502. The frame 502 has a thickness that varies along itslength to optimize strength where needed, yet minimize material (andtherefore crimp profile) at selected regions of the frame. In theembodiment shown, the outflow end portion 506 of the frame has a maximumthickness T₁ (measured from the inside diameter to the outside diameterof that portion of the frame) and the inflow end portion 508 of theframe has a minimum thickness T₂ (measured from the inside diameter tothe outside diameter of that portion of the frame). It should be notedthat the struts of the frame 502 (which are not shown in FIG. 59) thatform the outflow end portion 506 have a thickness T₁ and the struts thatform the inflow end portion 508 have a thickness T₂. The frame 502 canhave an identical construction to the frame 12 described above, exceptfor the variable thickness of the frame. The areas of reduced thicknesscan be formed using a variety of manufacturing techniques, such aselectro-polishing selected portions of the frame (the non-polishedportions can be masked), grinding selected portions of the frame, wirecutting, or other suitable techniques.

The outflow end portion 502 generally corresponds to the region of theframe that supports the commissures of the leaflets 504 and typicallyexperiences the greatest loading on the valve. Therefore the outflow endportion 502 of the frame has a greater thickness T₁ selected to providethe required strength under anticipated loads. The inflow end portion508 supports an additional layer of material by virtue of the outerskirt 18. The reduced thickness of the inflow end portion 508 allows theinflow end portion to be crimped to a smaller diameter than the outflowend portion. This offsets or minimizes the increase in the crimpdiameter caused by the addition of the outer skirt 18.

FIGS. 60-62 show an another embodiment of an implantable prostheticvalve 310 that comprises a leaflet structure 314 and a radiallycollapsible and expandable frame 312 (similar to the frame 50 shown inFIG. 11) having a plurality of radially spaced commissure windows 318that are used to secure the leaflet structure within the frame. Thevalve 310 also comprises a skirt 316 secured between the inner surfaceof the frame 312 and the curved lower edges 364 of the leaflet structure314. The valve 310 has a lower, inflow end 340 and an upper, outflow end342.

As shown in FIG. 60A, each window 318 comprises an enclosed opening 334between two axially extending side struts 320, respectively. Each sidestrut comprises a generally rectangular, e.g. square, cross-sectionalprofile, as shown in FIG. 63. Each rectangular side strut 320 comprisesfour surfaces: an exterior surface 324 on a radially outward facingside, and interior surface 326 on a radially inward facing side, amedial surface 328 on a side facing the other side strut, and a lateralsurface 330 on a side facing away from the other side strut. In otherembodiments, side struts can comprise other cross-sectional shapes, suchcircular or hexagonal.

The leaflet structure comprises a plurality of leaflets 360, eachcomprising a pair of side tabs 366 secured to the frame 312, a curvedlower edge 364 secured to the skirt 316, and an articulation portion 372between the side tabs and the lower edge. Each side tab 366 is pairedwith an adjacent side tab of another leaflet 360 to form commissures 376of the leaflet structure 314. Each pair of side tabs 366 extendsradially outwardly through a corresponding commissure window 318 to alocation outside of the frame 312 and is secured to the side struts 320of the window, such as with sutures, as shown in FIG. 62. In someembodiments, each side tab 366 comprises an end portion 368 (see FIG.64) and the two side tab end portions 368 of each commissure 376 extendcircumferentially away from one another and along the exterior surfaces324 of respective side struts 320 of the window 318.

In some embodiments, each commissure 376 further comprises at least onenon-rigid reinforcing sheet 378 sutured to the side tabs 366 and to theside struts 320. The sheets 378 can comprise a flexible, tear resistantmaterial, including a variety of natural and/or synthetic biocompatiblematerials. Exemplary synthetic materials can include polymers such asnylon, silicone, and polyesters, including PET. In one example, thesheets 378 comprise a woven PET fabric.

Each reinforcing sheet 378 can be generally rectangular (when laid flat)and can comprise a middle portion 380 and opposing end portions 386. Insome embodiments, a first end portion 386 of the sheet is secured to afirst side strut 320 and a second end portion 386 of the sheet issecured to the second side strut 320, as shown in FIG. 64. The sheet 378separates the side tabs 366 from the side struts 320 such that side tabsdo not contact the side struts. For example, each end portion 386 of thesheet can be wrapped completely around a respective side strut 320, asshown in FIG. 64.

The side tabs 366 and the reinforcing sheet 378 can be secured to theside struts 320 in multiple stages. For example, FIG. 63 shows anexemplary first suturing stage wherein the sheet is positioned such thatthe middle portion 380 of the sheet extends circumferentially acrossouter surfaces of the end portions 368 of the side tabs 366 and each endportion 386 of the sheet extends between a respective side tab 366 andthe exterior, medial and interior surfaces 324, 328, 326, respectively,of a respective side strut 320. The sheet 378 surrounds the side tabs366 and protects the side tabs from edges of the side struts 320. A pairof in-and-out sutures 390 can secure each side tab 366 and one end ofthe sheet 378 to a respective strut 320. As shown in FIG. 63, eachsuture 390 can be oriented generally perpendicularly to thecircumference of the frame 312 along the lateral surfaces 330 of theside struts 320 and can pass radially back and forth through thecommissure 376 at a plurality of difference longitudinal positions. Eachsuture 390 can intersect a first layer of the sheet 378, a side tab endportion 368, a second layer of the sheet, and a third layer of thesheet, in that order moving radially inward. The sutures 390 secure thesheet 378 to the side tab end portions 368 and tighten the sheet endportions 386 around the side struts 320, thereby securing the side tabs366 to the side struts 320 and securing the leaflet structure 314 to theframe 312.

FIG. 64 shows an exemplary second suturing stage wherein a second pairof sutures 392 are used to tie down loose portions of the reinforcingsheet 378. For example, the second sutures 392 can intersect theportions of the middle portion 380 and the end portions 386 of the sheetthat extend laterally beyond the first sutures 390. The second sutures392 can be helical whip stitches that intersect the commissures 376 at aplurality of different longitudinal positions, as shown in FIG. 62, andsecure the loose portions of the sheet 378 tightly against the lateralsurfaces 330 of the side struts.

Both the first sutures 390 and the second sutures 392 can be positionedadjacent to the lateral surfaces 330 of the struts 320 and spaced awayfrom the window opening 334. This placement of the sutures can reducethe stress on the sutures caused by movement of the articulationportions 372 of the leaflets. Instead, much of this stress istransferred from flex hinges 370 of the leaflets to the side struts 320near interior-medial edges 332 of the struts.

The reinforcing sheet 378 protects the flex hinges 370 from damagecaused by the interior-medial edges 332 of the struts 320 as theleaflets articulate between open and closed positions, as shown in FIG.64. In addition, some embodiments can also include longitudinallyextending cushion strips 374 positioned between the flex hinges 370 andthe struts 320, such as adjacent to the interior-medial edges 332, asshown in FIG. 64, to further protect the flex hinges from damage causedby the struts. The cushion strips 374 can comprise a flexible,compressible material, such as PET fabric, pericardial tissue, orvarious other biocompatible materials. In some embodiments, the cushionstrips can comprise a tube filled with a resilient material. Forexample, the cushion strip can comprise a PET tube filled withpericardial tissue. In other embodiments, the outer tubular covering ofthe cushion strips can be formed from sheet 378 and can be filled with aresilient material. The sheet can be secured around the resilientmaterial with sutures to retain the cushioning strips properly locatedas shown in FIG. 64. In other embodiments, separate cushion strips 374can be sutured to the reinforcing sheet 378. The cushion strips 374 canhave a thickness similar to the bars 62 to provide a radial clearancebetween the side struts 320 and the articulating portions 372 of theleaflets to prevent or minimize contact between the leaflets and theinner surface of the frame during the cardiac cycle.

FIG. 65 shows an embodiment similar to FIGS. 63 and 64 but with adifferent suturing pattern. In FIG. 65, the sutures 390 are replacedwith sutures 398 that secure the sheet 378 around the end portions 368of the side tabs. Each suture 398 intersects the middle portion 380 ofthe sheet, one of the side tabs 366, and a second layer of the sheetadjacent to the medial-exterior edge 324 of each side strut. The sutures398 can comprise in-and-out stitches that intersect the commissures at aplurality of different longitudinal positions. Each end portion of thesheet 378 can comprise a folded portion 388 that is folded under to forma double layer of the sheet 378 along the surface of the respective sidestrut 320. The sutures 392 secure the end portions 386 of the sheet andthe end portions 368 of the side tabs tightly around the lateralsurfaces 330 of the side struts.

FIGS. 66 and 67 show an alternative method for suturing the side tabs366 and the sheet 378 to the side struts 320. FIG. 66 shows suture line394 positioned along the exterior surfaces 324 of the side struts andgenerally perpendicular to the radius of the frame. The suture 394intersects both side tabs 366 and both end portions 386 of the sheet378. The suture 394 secures each end portion 386 of the sheet tightlyaround the medial, interior, and lateral surfaces 328, 326, 330,respectively, of the respective side strut 320, and also secures themiddle portion 380 of the sheet loosely around the end portions 368 ofthe side tabs 366. In the embodiment shown in FIG. 66, the suture 394intersects a first sheet layer A, a second sheet layer B, the two sidetabs 366, a third sheet layer C, and a fourth sheet layer D, in thatorder.

After the first suture 394 is in place, the end portions 368 of the sidetabs are spread apart and positioned adjacent to the exterior surfaces324 of the side struts 320, as shown in FIG. 67. This tightens the loosemiddle portion 380 of the sheet around the end portions 368 of the sidetabs. A pair of sutures 396 can then secure the middle portion 380 ofthe sheet tightly to the end portions 386 of the sheet to hold the endportions 368 of the side tabs in place, as shown in FIG. 67. The sutures396 can be looping whip stitches that intersect the commissure 376 at aplurality of different longitudinal positions, similar to the sutures392 in FIG. 64.

FIGS. 68 and 69 show another alternative method for suturing the sidetabs 366 and the sheet 378 to the side struts 320. FIG. 68 shows asuture line 395 positioned along the exterior side of the window openingand oriented generally perpendicular to the radius of the frame. Thesuture 395 intersects both side tabs 366 and two portions of the sheet378. The suture 395 secures the middle portion 380 of the sheet whichextends loosely around the end portions 368 of the side tabs 366. In theembodiment shown in FIG. 68, the suture 395 intersects a first sheetlayer A, a first side tab B, a second side tab C, and a second sheetlayer D, in that order.

After the first suture 395 is in place, the end portions 368 of the sidetabs are spread apart and positioned adjacent to the exterior surfaces324 of the side struts 320, as shown in FIG. 69. This tightens the loosemiddle portion 380 of the sheet around the end portions 368 of the sidetabs. A pair of sutures 397 can then secure the middle portion 380 ofthe sheet tightly to the end portions 386 of the sheet to hold the endportions 368 of the side tabs in place, as shown in FIG. 69. The endportions 386 of the sheet can comprise a folded under portion 388,creating a double layer of sheet material to reinforce the sutures 397.The sutures 397 can be looping whip stitches that intersect thecommissure 376 at a plurality of different longitudinal positions,similar to the sutures 392 in FIG. 62.

FIGS. 70 and 71 show yet another alternative method for suturing theside tabs 366 and the sheet 378 to the side struts 320. FIG. 70 showsthe suture line 395 positioned along the exterior side of the windowopening and oriented generally perpendicular to the radius of the frame.The suture 395 intersects both side tabs 366 and four portions or layersof the sheet 378. Each end portion 386 of the sheet comprises a foldedportion 388 that forms a double layer of sheet material between the sidetabs 366 and the medial surfaces 328 of the side struts. The suture 395secures the middle portion 380 of the sheet loosely around the endportions 368 of the side tabs 366. As shown in FIG. 70, each stitch ofthe suture 395 intersects a first pair of sheet layers comprising layersA and B, a first side tab C, a second side tab D, and a second pair ofsheet layers comprising layers E and F, in that order.

After the first suture 395 is in place, the end portions 368 of the sidetabs are spread apart and positioned adjacent to the exterior surfaces324 of the side struts 320, as shown in FIG. 71. This tightens themiddle portion 380 of the sheet around the end portions 368 of the sidetabs. A pair of sutures 397 can then secure the middle portion 380 ofthe sheet tightly to the end portions 386 of the sheet to hold the endportions 368 of the side tabs in place, as shown in FIG. 71. The foldedportions 388 of the sheet create a double layer of sheet material toreinforce the sutures 397. The sutures 397 can be looping whip stitchesthat intersect the commissure 376 at a plurality of differentlongitudinal positions, similar to the sutures 392 in FIG. 62.

The commissure various configurations for attaching the leafletstructure 314 to the window frames 318 shown in FIGS. 61-71 can also beused as alternative ways to attach the leaflet structure 14 of the valve10 of FIGS. 1-3 to the window frame portions 30 of frame 12.

FIGS. 72-74 show a prosthetic heart valve assembly 600 comprising anembodiment of a frame 602 for a prosthetic valve mounted on a balloon606 of a delivery shaft 604. The frame 602 can be similar in shape tothe frame 12 and can comprise in inflow end portion 610, an outflow endportion 612 and an intermediate portion 614. For clarity, the othercomponents of the valve, such as the leaflets and the skirts, are notshown. The frame 602 can have a reduced thickness at the inflow endportion 610 and at the outflow end portion 612, relative to thethickness of the intermediate portion 614. Due to the thinner endportions, when the balloon 606 is inflated the end portions 610, 612offer less resistance to expansion and expand faster than theintermediate portion 614, as shown in FIG. 73. Because the end portionsexpand faster than the intermediate portion, the frame 602 becomesconfined on the balloon 606, inhibiting the frame from sliding towardseither end of the balloon and reducing the risk of the frame sliding offthe balloon prematurely. As shown in FIG. 74, further inflation of theballoon can cause the intermediate portion 614 of the frame to expand tothe same final diameter as the end portions 610, 612 for implantation,after which the balloon can be deflated and removed. Controlling theposition of the valve on the balloon can be important during delivery,especially with frames that foreshorten during expansion and moverelative to the balloon. In the embodiment shown in FIGS. 72-74, theintermediate portion 614 of the frame can be held constant relative tothe balloon while the two end portions foreshorten towards theintermediate portion due to the “dog-bone” effect of the balloon. Anyconventional means can be used to produce the frame 602 with reducedthickness at the end portions 610, 612, such as sanding down the endportions with sand paper or the like. In one embodiment, the endportions 610, 614 of the frame have a thickness of about 0.37 mm whilethe intermediate portion 614 has a thickness of about 0.45 mm.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope of these claims.

The invention claimed is:
 1. An implantable prosthetic heart valve thatis radially collapsible to a collapsed configuration and radiallyexpandable to an expanded configuration, the prosthetic heart valvecomprising: a radially expandable annular frame comprising plasticallydeformable material selected from group comprising stainless steel andcobalt-chromium alloy; wherein the frame comprises an inflow end portiondefining an inflow end of the frame that is configured to receiveantegrade blood flow into the prosthetic heart valve when implantedwithin a patient's body in the expanded configuration, and the framealso comprises an outflow end portion defining an outflow end of theframe opposite the inflow end of the frame; wherein the frame comprisesan inflow ring of honeycomb shaped hexagonal openings at the inflow endportion of the frame and en outflow ring of honeycomb shaped hexagonalopenings at the outflow end of the frame, the outflow ring of honeycombshaped hexagonal openings being a closest ring of openings to theoutflow end of the frame; wherein the entire frame has a generallycylindrical shape; wherein the hexagonal openings of the inflow ring aredefined by a circumferentially extending first row of angled strutsarranged end-to-end, a circumferentially extending second row (Wangledstruts arranged end-to-end, and a plurality of axially extending strutsinterconnecting the first and second rows of angled struts; and whereinthe each of the axially extending struts joins to a U-shaped crownstructure joining adjacent ends of struts of the first row of angledstruts and joins to a U-shaped crown structure joining adjacent ends ofstruts of the second row of angled struts.
 2. The valve of claim 1,wherein the axially extending struts are thinner than the U-shaped crownstructures of the first and second rows.
 3. The valve of claim 1,wherein the plurality of axially extending struts constitute a row ofaxial struts that is less dense than first and second rows of angledstruts.
 4. The valve of claim 3, wherein row of axial struts includesfewer struts than the first and second rows of angled struts.
 5. Thevalve of claim 1, wherein inflow ring has 12 hexagonal openings.
 6. Thevalve of claim 1, wherein the U-shaped crown structures joining adjacentends of struts of the second row of angled struts are inverted relativeto the U-shaped crown structures joining adjacent ends of struts of thefirst row of angled struts.
 7. The valve of claim 1, wherein thehexagonal openings of the outflow ring are larger than the hexagonalopenings of the inflow ring.
 8. The valve of claim 1, wherein theoutflow ring further comprises three rectangular openings that receivecommissures of a leaflet valve structure.
 9. The valve of claim 1,further comprising at least one intermediate ring of openings betweenthe inflow ring and the outflow ring.
 10. The valve of claim 9, whereinthe openings of the outflow ring are larger than the openings of the atleast one intermediate ring.
 11. An assembly comprising: a deliverycatheter having an inflatable balloon; and an implantable prostheticheart valve mounted on the delivery catheter, wherein the prostheticheart valve is radially collapsible to a collapsed configuration andballoon expandable to an expanded configuration, the prosthetic heartvalve comprising a radially expandable annular frame comprising aninflow end portion defining an inflow end of the frame that isconfigured to receive antegrade blood flow into the prosthetic heartvalve when implanted within a patient's body in the expandedconfiguration, and the frame also comprises an outflow end portiondefining an outflow end of the frame opposite the inflow end of theframe; wherein the frame comprises an inflow ring of honeycomb shapedhexagonal openings at the inflow end portion of the frame and an outflowring of honeycomb shaped hexagonal openings at the outflow end of theframe, the outflow ring of honeycomb shaped hexagonal openings being aclosest ring of openings to the outflow end of the frame; wherein theentire frame has a generally cylindrical shape; wherein the hexagonalopenings of the inflow ring are defined by a circumferentially extendingfirst row of angled struts arranged end-to-end, a circumferentiallyextending second row of angled struts arranged end-to-end, and aplurality of axially extending struts interconnecting the first andsecond rows of angled struts; and wherein the each of the axiallyextending struts joins to a U-shaped crown structure joining adjacentends of struts of the first row of angled struts and joins to a U-shapedcrown structure joining adjacent ends of struts of the second row ofangled struts.
 12. The assembly of claim 11, wherein the axiallyextending struts are thinner than the U-shaped crown structures of thefirst and second rows.
 13. The assembly of claim 11, wherein theplurality of axially extending struts constitute a row of axial strutsthat is less dense than first and second rows of angled struts.
 14. Theassembly of claim 13, wherein row of axial struts includes fewer strutsthan the first and second rows of angled struts.
 15. The assembly ofclaim 11, wherein the U-shaped crown structures joining adjacent ends ofstruts of the second row of angled struts are inverted relative to theU-shaped crown structures joining adjacent ends of struts of the firstrow of angled struts.
 16. The assembly of claim 11, wherein thehexagonal openings of the outflow ring are larger than the hexagonalopenings of the inflow ring.
 17. The assembly of claim 11, furthercomprising at least one intermediate ring of openings between the inflowring and the outflow ring.
 18. The assembly of claim 11, wherein theopenings of the outflow ring are larger than the openings of the atleast one intermediate ring.